> From: Brandon High [mailto:bh...@freaks.com] > > On Thu, Jan 6, 2011 at 5:33 AM, Edward Ned Harvey > <opensolarisisdeadlongliveopensola...@nedharvey.com> wrote: > > But the conclusion remains the same: Redundancy is not needed at the > > client, because any data corruption the client could possibly see from the > > server would be transient and self-correcting. > > Weren't you just chastising someone else for not using redundancy over > iSCSI?
I wouldn't say chastising... But yes. But that was different. The difference is whether or not the iscsi target is using ZFS. If the iscsi target is a typical SAN made of typical hardware raid, then there is no checksumming happening at the per-disk per-block level, and the raid redundancy only protects against hardware-detected complete disk failure. Any data corruption undetected by hardware is uncorrectable by software in that case. The situation is much better when your iscsi target is in fact a ZFS server. Because if there's a checksum error on a disk, it's detected and correctable by ZFS. So the iscsi initiator will not see any corrupt data. The point that I keep emphasizing is: Let ZFS manage your raid. No hardware raid. As mentioned, sure there's always the possibility of an error being introduced in the network between initiator & target, but ultimately the nonvolatile storage is disk, which has good data. So the possibility of transient network errors, at least for me, is much less risky than the possibility of undetected error on disk. _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
